Blackpowder was one of the first materials that could be used as a propellant, an explosive, and in pyrotechnic devices. The Chinese are credited with its development many centuries ago. As blackpowder characteristics became known, its uses expanded. It was first used in cannons and hand cannons in Europe in the 14th century. It began to be used in civil engineering projects in the 16th century and in coal mining operations during the 17th century. The forerunner of today's muzzleloading guns, the matchlock musket, was also invented in the 16th century. Following that matchlock, further developments in firearms made the use of blackpowder more effective and convenient. In rapid succession, better ignition systems were developed with both the wheellock and the flintlock during the 16th century. The percussion cap firearm, similar to that used today, was not developed until the 19th century.
Thus, for hundreds of years, blackpowder remained unchallenged as the only material of its type. Inventors directed their efforts to making better use of blackpowder. With the advent of nitro-cellulose smokeless powder in the latter part of the 19th century, blackpowder lost its preeminence as the only gun propellant. Smokeless powder burned cleaner and produced more energy than did blackpowder, and it was safer to use and handle. However, because of blackpowder's lower gun barrel pressures, ignition characteristics, and low cost of manufacture, blackpowder retained its place in the market as the only propellant for antique firearms such as muzzleloaders and the preferred material for use in fuse manufacture, ignition devices, cannon round igniters, fireworks, and the like.
In 1978, U.S. Pat. No. 4,128,443 was issued to Pawlak and Levenson for Deflagrating Propellant Compositions. Blackpowder was soon no longer the muzzleloading propellant of choice for many sportsmen. The principal product marketed as a result of the Pawlak et. al. patent is known as Pyrodex powder. This product does not detonate and is less prone to accidental ignition than is blackpowder. In addition to being used as a propellant in muzzleloading and cartridge guns, Pyrodex powder has been formulated as a delay powder, a fuse powder, a fireworks powder, and in some military applications. However, Pyrodex it not without its own drawbacks. It does not ignite satisfactorily in flintlock guns and, like blackpowder, it contains sulfur which results in combustion residues that are hard to remove and can cause corrosion if left in the gun barrel.
U.S. Pat. No. 4,497,676 issued in 1985 to Kurtz. It was the first in a number of patents on sulfur-free compositions utilizing potassium nitrate and ascorbic or erythorbic acid. Some of these patents used slurries in the manufacture thus requiring the subsequent removal of large quantities of water. Others required cooking or heating with the attendant high production cost and hazard. Many of these products had low energy content and were very hygroscopic with the result that the product coagulated in the container, becoming a single, unusable lump.
Cioffe further expanded on the use of ascorbic or erythorbic acid in U.S. Pat. No. 5,449,423 by adding potassium perchlorate. This product had reduced hygroscopicity and higher energy, however, it requires high energy inputs during manufacture for compaction and subsequent granulation. The resulting product has been known to detonate. Other similar products are known that have the same bad characteristics.
Several factors have combined to increase the market for a clean burning, high performance propellant composition. Deer population in many states has grown substantially due to good conservation management, and these states now have separate seasons for muzzleloading guns during a so-called primitive weapons season, as well as a regular season for conventional, high powered firearms. The same is true in many western states having elk herds. Due to the growing popularity of muzzleloaders, gun manufacturers have developed the “in line” rifle which gives better ignition than the side-hammer percussion rifle, and these weapons are made to withstand higher gun barrel pressures. When Pyrodex powder was first introduced, the most popular projectile was the patched round ball. Today, modern projectiles using plastic sabots with a metal jacketed bullet are gaining ascendance and higher velocities are desirable.
The demand is growing for propellant compositions that will keep pace with expanding market of shooters and sportsmen having an interest in muzzleloading type weaponry. At the same time, the need remains for propellant compositions which solve the many disadvantages and drawbacks of corrosiveness and cleaning difficulty associated with blackpowder and conventional blackpowder substitutes such as Pyrodex powder. The primary objective of this invention is to meet these needs.